1. Technical Field
The present invention relates to a soft magnetic powder, a powder magnetic core, a magnetic element, and an electronic device.
2. Related Art
Recently, reduction in the size and weight of mobile devices such as notebook personal computers has advanced. However, in order to achieve both reduction in the size and enhancement of the performance, it is necessary to increase the frequency of a switching power supply. At present, the driving frequency of a switching power supply has been increased to about several hundred megahertz. However, accompanying this, it is also necessary to increase the frequency of a magnetic element such as a choke coil or an inductor which is built into a mobile device.
For example, JP-A-2004-349585 discloses a powder magnetic core, which is a powder magnetic core containing a magnetic powder having a composition represented by Fe(100-X-Y-Z-α-β)BXSiYCuZMαM′β (at %) (wherein M is at least one element selected from the group consisting of Nb, W, Ta, Zr, Hf, Ti, and Mo, M′ is at least one element selected from the group consisting of V, Cr, Mn, Al, a platinum group element, Sc, Y, Au, Zn, Sn, Re, and Ag, and X, Y, Z, α, and β satisfy the following formulae: 12≤X≤15, 0<Y≤15, 0.1≤Z≤3, 0.1≤α≤30, and 0≤β≤10, respectively), wherein the magnetic powder which is either a nanocrystalline magnetic powder containing a nanocrystalline structure having a crystalline particle diameter of 100 nm or less in an amount of at least 50% or more of the structure or an amorphous magnetic powder having a composition capable of exhibiting the nanocrystalline structure by a heat treatment is contained.
In the powder magnetic core described in JP-A-2004-349585, magnetic powder particles are insulated from each other by an insulating material such as a glass material. By insulating the particles from each other, an eddy current loss at a high frequency can be reduced. However, when the proportion of the insulating material is decreased, the magnetic powder particles are likely to come into contact with each other, and therefore, the insulating properties between the particles cannot be ensured. Due to this, the insulating material is needed in a relatively large amount. However, when the proportion of the insulating material is increased, the proportion of the magnetic powder in the powder magnetic core is decreased, and thus, the magnetic properties of the powder magnetic core cannot be sufficiently enhanced.